William of Ockham (also Occam, from Latin: Gulielmus Occamus; c. 1287 – 1347) is an English Franciscan friar and scholastic philosopher and theologian, who is believed to have been born in Ockham, a small village in Surrey.

He is considered to be one of the major figures of medieval thought and is at the center of the major intellectual and political controversies of the fourteenth century.

He is commonly known for Occam's razor, the methodological principle that bears his name, and also produces significant works on logic, physics, and theology.

In the Church of England, his day of commemoration is 10 April.